Lubricating oil and method of preparing the same



PATENT OFFICE LUBRICATING OIL AND IVIETHOD F PREPARING THE SAME CharlesC. Towne, Beacon, N. Y., assignor to The Texas Company, New York, N. Y.,a corporation of Delaware No Drawing. Application March 23, 1936,

Serial No. 70,402

8 Claims.

presence of halides and halogen acids of tin and.

boron, the purification of this resinous polymer, and the compounding ofthese materials with mineral lubricating oil, are described. In theproduction of the resinous polymer in accordance with the mentionedapplications, it is found that a substantial proportion of oil insolublepolymer is also produced, which of course is unsuited for compoundingwith lubricating oils.

In accordance with the present invention, a

resinous polymer is produced from rubber which is substantiallycompletely oil soluble, so that the entire yield of resinous product canbe employed for compounding with lubricating oils. At the same time, itis found thatthis improved material, when compounded with a mineral oil,possesses further advantages including increased stability when heated,better color stability, less viscosity change and greater freedom fromsludge separation. The proportion of reagents required is also reduced,thereby efiecting a further economical advantage. The material of thepresent invention is eminently suited for compounding with motor oils toproduce a lubricating oil of improved character having a high viscosityindex.

In accordance with the present invention, rubber in dispersion in asuitable aromatic solvent, such as benzol, is treated with adepolymerizing agent. This is accomplished by allowing the rubberdispersion to stand for a period of time, generally about 24 hours, inthe presence of such a depolymerizing agent. Examples of suitabledepolymerizing agents for this purpose are glacial acetic acid,hydrochloric acid, chlor-acetic acid, sulfur dioxide, hydrogen sulfide,benzoic acid, mercurous chloride and ammonia. The result of thistreatment is to modify the rubber, giving a product of lower molecularweight and consequently termed depolymerized.

The dispersion of depolymerized rubber is then treated with one of agroup of compounds consisting of halides and halogen acids of tin andboron, such as stannic chloride or bromide, boron trichloride, boronfluoride, fluorboric acid, chlorostannic acid, chloro-stannous acid andthe corresponding brom acids. Anhydrous stannic chloride is preferredfor this purpose. The reaction 60 takes place by standing at roomtemperature for a period of time, such as about 24 hours. The resultingresinous polymer is then precipitated by admixing with a suitableprecipitating solvent, such as an alcohol or a ketone. For example, verysatisfactory results are secured with 95% ethyl alcohol, acetonecontaining about water, and methyl alcohol containing about 5% water.The precipitate is then filtered, washed free of acid with additionalprecipitating solvent, and dried.

The resulting product is a white resinous polymer, which is very lightin weight and powdery in appearance. It is substantially completelysoluble in a mineral lubricating oil in proportions up to about 40% byweight. It possesses unusual viscosity index increasing properties, sothat the addition of about 2%-3% of the polymer to a mineral lubricatingoil serves to increase the viscosity index thereof very materially. Theresuiting lubricating oil solution may be slightly cloudy, but this iscleared by clay contacting at elevated temperatures, producing a pale,clear, bright oil.

As a specific example of the invention 50 g. of crepe rubber isdispersed in 1500 cc. of benzol (90%) containing 15 cc. of glacialacetic acid. The dispersion is allowed to stand 24 hours, and the air isthen swept out with a nitrogen strea To this depolymerized rubberdispersion, there is added 10 cc. of anhydrous fuming stannic chloride.The mixture is allowed to stand 24 hours at room temperature. Theproduct is then -run into 3500 cc. of 95% ethyl alcohol, which efi'ectsprecipitation of the resinous polymer. The precipitation is completed bystirring for 2-3 hours. The precipitated polymer is then filtered off,washed free of acid with alcohol, and dried. A yield of 96% by weight ofresinous polymer on the weight of the rubber used was obtained in theabove example. The entire yield of resinous polymer was soluble in alubricating oil.

It is found that the proportion of depolymerizing agent employed has aneffect upon the yield of the soluble polymer.

ing oil. Where 5 cc. of acetic acid is employed with the above mentionedproportions, a substantial quantity of insoluble polymer is stillproduced, although the yield of precipitate is substantially l00,% onthe weight of the rubber used. Where larger quantities of glacial aceticacid than 15 cc. for the above mentioned proportions of otheringredients are employed, the entire precipitate is oil soluble butthere is no apparent advantage in the use of the larger proportions.Consequently, for most economical production of oil soluble polymer, itis desirable to predetermine the proportion or depolymerizing agentemployed so as to render the entire precipitate substan- I For example,where no glacial acetic acid is employed, about 50% of the resultingprecipitate is insoluble in lubricattially completely oil soluble andstill give an optimum yield of the soluble polymer.

Not only is an optimum yield of oil soluble polymer obtained inaccordance with the present invention, but this polymer when compoundedwith mineral lubricating oil possesses superior properties. The materialis highly effective in improving the viscosity index of the oil, and thecompounded oil possesses increased stability when heated, as isreflected in better color, less viscosity change and greater freedomfrom sludge separation.

The following is an example of a compounded oil prepared by the additionof 3% by weight of the. resinous polymer to furfural refined Mid-Continent lubricating distillate consisting of 58.2% by weight of an S.A. E. #10 oil and 38.8% by weight of an S. A. E. #20 oil. The propertiesof the base oils as well; as the compounded oil are as follows:

S. A. E. S. A. E Compound- #10 #20 ed oil Gravity, A. P I 31. 27. 0Flash, F 395 445 Fire, F 450 495 Viscosity SIT/ F. 172 351- 433Viscosity SU/210" F 44. 6 53.3 63. 2 Viscosity indexDean & Davis 97 82112 Carbon residue, percent 02 05 06 Neutralization N o 03 As indicativeof the superior stability of the resinous polymer prepared in accordancewith the present invention, in comparison to that obtained by directtreatment of rubber with stannic chloride without first depolymerizingthe same, the following data obtained by heating the base oil and thecompounded oils for three days at a temperature of C. in an airatmosphere, is given:

Base oils com- Base oils conpiimnded gvtith taminl g p0 ymer 0 ampo ymerBase 0118 ed without prepared by preliminary depreliminarydepolymerization polymerization Before After Before After Before, Afterheatheath'eatheatheatheating ing ing ing ing ing Vis. Bil/100 F 222 225392 361 383 371 Vis. change- +3 31 -12 Obviously many modifications andvariations of the invention, as herein-before set forth, may bemade'without departing from the spirit and scope thereof, and thereforeonly such limitations should be imposed as are indicated in the appendedclaims.

I claim:

1. The method in the manufacture of a lubrieating oil of improvedcharacter, which comprises depolymerizing a dispersion of rubber in anaromatic solvent with a depolymerizing agent, reacting the depolymerizedrubber in the presence of one, of a group of compounds consistingofhalides and halogen acids of tin and boron to produce a resinouspolymer, precipitating and separating the resinous polymer, anddissolving the polymer in a minor proportion in a petroleum lubricatingoil.

2. The method in the manufacture of a lubrieating oil of improvedcharacter, which comprises depolymerizing a dispersion of rubber in anarcmatic solvent with a depolymerizing agent, reacting the depolymerizedrubber in the presence of one of a group of compounds consisting ofhalides and halogen acids of tin and boron to produce a resinouspolymer, precipitating and separating the resinous polymer, dissolvingthe polymer in a minor proportion in a petroleum lubricating oil, andclay contacting the lubricating oil solution of resinous polymer.

3. The method in the manufacture of a lubricating oil of improvedcharacter, which comprises depolymerizing a dispersion of rubber in anaromatic solvent in the presence of a depolymerizing agent selected fromthe group consisting of glacial acetic acid, hydrochloric acid,chlor-acetic acid, acidified benzene, sulfur dioxide, hydrogen sulfide,and benzoic acid, then reacting the depolymerized rubber in the presenceof anhydrous stannic chloride to produce a resinous polymer,precipitating and separating the resinous polymer from the reactionmixture, and dissolving the separated resinous polymer in a minorproportion in a petroleum lubricating oil.

4. An improved lubricating oil comprising a petroleum lubricating oilcontaining dissolved therein to a clear solution a minor proportion of aresinous polymer which is the reaction product of depolymerized rubberwith one of a group of compounds consisting of halides and halogen acidsof tin and boron.

'5. An improved lubricating oil comprising a petroleum lubricating oilcontaining dissolved therein to a clear solution a minor proportion of aresinous polymer which is the reaction product with anhydrous stannicchloride of rubber depolymerized by the action of a depolymerizing agentselected from the group consisting of glacial acetic acid, hydrochloricacid, chlor-acetic acid, acidified benzene, sulfur dioxide, hydrogensulfide, and benzoic acid.

6. An improved lubricating oil comprising a petroleum lubricating oilcontaining dissolved therein to a clear solution a minor proportion of aresinous polymer which is the reaction product with anhydrous stannicchloride of rubber depolymerized in dispersion in an aromatic solvent inthe presence of glacial acetic acid.

7. The method in the manufacture of a lubricating oil of improvedcharacter, which comprises dispersing rubber in an-aromatic solvent inthe presence of a depolymerizing agent and,

reacting with one of a group of compounds consisting of halides andhalogen acids of tin and boron to produce a substantially completelyoilsoluble resinous polymer from the rubber, precipitating andseparating the resinous polymer, and dissolving the polymer in a minorproportion in a petroleum lubricating oil.

